Stabilization of polyvinyl formal



' to acid. To this is added 83 parts of an aqueous hibits the decomposition of the resinous material 16 38. tent to which the polyvinyl ester has been conty-eight grams of the thread-like solid condensa- 4o molding compositions, and for'various'other purcondensation product not treated as above de- I so insoluble and infusible state. able manner, with the resin during its prepara- UNITED STATES A-rear omen sienna s'rssmzs'nos or romrvmxa roman Birger W. Nordlander, Schenectady, 8. assignor to General Electric Company, a entporation of New York No Application June 22, 1981, Serial No. 149.068 v 4 Claims. (CL 260-78) This inventionrelates broadly to an improved tions where the original lightcolor of the maresinous composition. The invention is more parterial, or its transparency in film form as-well as ticularly concerned with a resinous material ob-' its original color, is desirable, for instance in the tained by condensing formaldehyde and a hymanufacture of laminated glass.

drolysis product of polyvinyl ester (for example, In accordance with the. present invention the 5 polyvinyl acetate, polyvinyl'butyrate or polyvinyl afore-described cond nsation product is mapropionate) and with which is incorporated certerially stabilized against the effects-of heat and tain substances of a phenolic nature that stabioxygen by incorporating therewith a small lize the condensation product. amount, for example about 0.1 to 2.0 per cent 10 The resinous material whichis stabilizedin acby weight of the whole, of a substituted phenol m cordance with the present invention may be preselected from the class consisting of para-phenyl pared, for instance, as follows: a phenol, para-tertiary butyl phenol, para-tertiary One hundred parts of a polymerized vinyl amyl' phenol and ortho-hydroxymethyl .phenol acetate is dissolved in 185 parts of glacial acetic (saligenin) The presence ofsuch substances insolution of formaldehyde, containing 37% per when exposed to heat and oxygen, as evidenced, cent of formaldehyde, and a suitable amount of for example. by retention of its original color. mineral acid, for example 6.8 parts of concensolubility an filfl lty to an extent not Possible trated sulfuric acid. All proportions herein givenv when the resin as normally produced is similarly Q0 are by weight. Hydrolysis is carried out at about exposed.

C. in an enameled vessel. Samples of the re- For purpose of illustration the following speaction mixture are removed at suitable intervals ciilc example is given: of time and analyzed for their formaldehyde con- Two grams of para-tertiary amyl phenol was tent. The results of analyses indicate the exdissolved in asolvent such as ethyl ether. Nineverted into polyvinyl formal. when the desired tion product herein described was treated with degree of conversion has been effected, a suitable this solution, in which it was substantially inamount of a neutralizingzagent, for example, 13 soluble, and constantly stirred while evaporatparts of concentratedammonia, is added to the ing' the solvent. The resulting product, which rereaction vessel. The neutralized mass is poured tained its thread-like shape, was placed in a 30 as a thin stream into water, whereupon the reglass vessel. The vessel was then put into an action product is precipitated in the formof oven having an air atmosphere and maintained threads. The thread-like material is washed at a temperature of about C. After 20 hours with water and-dried in a current of warm (60 exposure the material had the same color as at as C.) air. 7 The dried threads are white, or nearly the beginning of the experiment. After 35 hours 35 so. In the form of solutions, films. sheets, etc., exposure the sample had assumed only a very g alone or modified with addition agents, the prodlight yellowish color, had not shrunk appreciably net is useful as adhesives, as impregnating agents, and .was almost completely soluble in the comin making laminated products and thermoplastic mon solvents for the material. A sample of the poses. Resinous compositions of the kind above scribed, and exposed simultaneously with the described decompose uponheating in air or oxytreated sample to the same conditions of heat 'gen,'giving of! volatile products, of which formaland-air, soon began to darken. After 20 hours dehyde, formic acid and other organic acids, car- -exposure the color had turned to brown and 4s bon dioxide and water have been identified. The after 35 hours it was deep brown. A considerable 5 decomposition is accompanied by a shrinkage and shrinkage also had taken place, and the material discoloration of the product and also, depending was practically insoluble in solvents in which it upon time and temperature conditions, by a paroriginally was soluble. v

" tial or complete conversion of the resin to the The inhibitor maybe incorporated, in any suit- For certain applications this instability of the tion or with the finished resin in solid or solution material is objectionable, for example in extrustate. For instance, the solid inhibitor may be sion processes where the initially plastic mass ground with the resin, or, as in the cited example, may set up in the extrusion head or chamber and it may be depositedfrom solution state on the is render the process diflicult; and, also. in applicasolid resin. Or, the inhibitor may be dissolved u l drolysis product of polyvinyl ester in a solvent and be added in solution form to the resin dissolved in the same or a difl'erent solvent. The solvent is then evaporated, leaving the inhibitor distributed throughout the resin.

gt i. theUnited tates is impro'vi s doxyg n of a'fre'sinous in'ate obtained by condensing formaldehyde with a h which 00 prises incorporating with saidxa nateria amount of ortho-hydroxymethylpheno 2. The method of improving against heat and oxygen (Sf-a resinous 15 tion comprising the product of condensing formaldehyde with a product of hydrolysis: oi'iz'kpoly vinyl acetate which consists in incorporating with said composition about 0.1 to 2.0 percent by -hydroxyme weight of the whole of oi'th What/I cla'hmas new and desire tosecureby .7 Bette 3. 'A composition of, matter which is resistant to discoloration under the influence of heat and oxygen and which contains as essential ingrediv cuts the resinous material obtained by condens- "lug-"formaldehyde: ydrolysisproduct.;oi;i mining! dhesite 'iiompo'sition "for *biiniii'ng al erms. inaddi't fdi 'i theftdfa small rthozhydronymethyl pheno l gather laminated glass, .said composition being "resistant to discoloration under the influence of h a gredi andvoxygen anda containing as essential innt the. roduct of condensing formaldect oI hydrolysis of polyvinyl dition thereto, from 0.1 to 2.0 htof the whole of ortho-hytd oxymeth'ylzphenol thereby to inhibit the deho'mposition and accompanying discoloration of the saidwresinous material when exposed to heat 1 maGEaw; NORI-DLANDE. 

